Rotary hook mechanism for sewing machines



July 3, 1934. M. l.. WATERMAN ROTARY Hoox MECHANISM RoR SEWING MACHINES Fi1ed.Apri1 9, 1952 gmc/nto@ Max L. Wafermal;

Patented July 3, 1934 ROTARY HOOK MCHANISM Fon SEWING MAcHnms Max L. Waterman, Fairfield, Conn., .assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application April 9, 1932, serial No. 604,133 1s`c1aims. (c1. i12- 181) This invention relates to sewing machines and more particularly to lock-stitch sewing machines in which the loop-taker makes a plurality of revolutions during each stitch-forming cycle.

'.5 One of the objects of this invention is'to improve the thread-handling conditions of lockstitch sewing machines.

vAnother object of this invention is to improve the frame structure of the machine to facilitate ,10 assembly and lubrication of the machine mechamsm.

With the above land other objects in view, as will hereinafter appear, the invention consists in the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawing of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those 0 skilled in the art.

This invention will be understood by reference to the accompanying drawing in which:

Figure 1 is a front elevation, partly in section, of the bed and loop-taker actuating mechanism of a sewing machine embodying my invention.

Figure 2 is a section taken along the line 2 -2 of Figure 1.

Figure 3 is a section taken along the line 3-3 of Figure 1.

In the embodiment of this invention selected for illustration, the machine is constructed with the usual bed-plate 1, gooseneck 2 rising therefrom, needle 3 reciprocable in a fixed-.path and presser-foot 4. Fixed to the under side of the bed-plate 1 by the cap-screws 5 is a troughshaped casing or sub-frame 6 having suitable bearings V"l in which is journaled the loop-taker actuating shaft 8. The main shaft of the sew- 0 ing machine (not shown) 'is connected, by the clip-belt 11, in driving relation with the beltwheel 9,` fixed to the loop-taker actuating shaft 8 by the set-screws 10. The shaft 8 receives one rotation for each rotation of the main shaft, and hencefor each reciprocation of the needle.

Fixed to the shaft 8 is a disk 12 provided with a stud 13 which is connected by a link 14 to a corresponding stud 15 on the gear-wheel'l which is fixed by the set-screws 18 to the shortrshaft 17 journaled in a suitable bearing 19 in thev casing 6 and held in operative position by a collar 20 fixed to the shaft 17 by set-screws21. The shafts 8 and 17, which are disposed in parallel relation, have their centers out of line or offset relative to each other,l thus causing the Short Formed in the casing 6 is a bearing22 loc-ated vabove the short shaft 17. The loop-taker shaft 23 is journaled in the bearing 22, and has fixed 60 to one end a gear 24 meshing with the gear 16. The ratio of the gears 16 and 24 is as 1 'is to 2, the gear 24 and shaft 23 making two complete revolutions for eachrevolution of the gear 16 and shaft 17. Fixed to the shaft 23 at its other'end 65 is the usual loop-taker 25 adapted to cooperate with the needle 3.

Journaled in the bearing 26 is a rock-shaft 27 having secured upon its rearward end by the setscrews 28 a bifurcated arm 29 which embraces 70 the actuating eccentric 30 fixed on the-short shaft 17. Fixed to the forward end of the rockshaft 27 by the screws 31 is a thread-case opening arm 32 which engages the usual lug 33 on the thread-case 34. By this means the rock-shaft 27 receives an oscillation for each rotation of the short shaft 17; consequently the thread-case opening arm 32 engages the lug 33 on the threadcase and opens a passage for the needle-thread loop to pass the thread-case rotation-restraining finger 35 once for each rotation of the shaft 8.

The machine, in the present instance, is provided With a four-motion lower feed-dog 36 which is actuated in the usual and well known manner. It is obvious that any of the well known types of work-advancing feeds may be employed.

The rotary-hook in machines of the class herein described is usually given two complete rotations for each needle-reciprocation for proper cooperation with the other elements involved in the handling of the thread. During its irst rotation, the hook seizes and casts the needle-loop around the lower thread-mass, this occurring during the upward movement of the needle. The second rotation of the hook, which occurs during the descent of the needle, is an idle one. `It has long been known that.there is not suicient time between the point in the cycle in which the needle-thread loop has been cast olf the hook and the point in which the needle re-enters the 100 work, for the take-up to function properly'and the feed to advance the work. Attempts have been made to overcome this diiculty, as for instance, by imparting to the rotary-hook three rotationsr for each stitch-forming cycle. When 105 a machine having a hook of this type is operated at high speed, the speed of rotation of the hook is .so excessive as to very materially increase wear and/ friction-induced heating of the parts. In ordfer to overcome this difficulty, I have provided 110 the rotary-hook during the loop-seizing and cast-01T part of the stitch-forming cycle and a, retarded rotation during the take-up and workfeeding part of the cycle.

In'the operation of the machine the shaft 8 is driven through one complete rotation at a uniform speed for each reciprocation of the needle or each stitch-forming cycle. Each rotation of the shaft 8 is communicated to the hookshaft 23, 4by means of the described connections,

. to produce alternate accelerated and retarded rotations of the hook or loop-taker, the one to two ratio of the gears 16, 24, distributing the acceleration and retardation of the shaft 17 to two successive rotations of the shaft 23 for each needle-reciprocation. It will be obvious that the acceleration of the loop-taker 25 during the loopseizing part of the cycle causes the needle-thread loop to be seized and cast off earlier in the cycle, thus giving more time for the take-up to set the stitch and the feed-dog to advance the work.

It will be observed that the loop-taker actuating mechanism is journaled in the trough-shaped casing 6, and that the loop-taker 25 together with its actuating mechanism and the casing 6 form a unitary structure which may be assembled at some distant point, and later, when the entire machine is assembled, be secured to the bedplate 1 by the screws 5, thus greatly simplifying the assembling of the machine. It will also be observed that the casing 6, forming a support for the loop-taker 25 and its actuating means, is so constructed as to provide a gear housing to eliminate the noise of the gear-drive and variable motion connection and that it also provides a lubricant reservoir, as shown at 37 in Figure 3.

To lubricate the bearing of the shafts 23, 17, and 27 from above the bed-plate, a single lubricant conduit 37 is provided in the casing 6. The conduit 37 connects the three bearing bushings 22, 19 and 26 which are provided with lubricantreceiving apertures 22', 19 and 26 and lubricant by-passing grooves 22, 19" and 26", respectively. The upper end of the conduit 37 has a funnelshaped mouth 37 which communicates with the lubricant-aperture 38 in the bed-plate 1. The lubricant-aperture 38 is normally sealed by a spring-pressed ball 39 to prevent lint, dust and other foreign matter from entering the lubricantconduit 37. Likewise, to lubricate the bearing for the forward end of the actuating shaft 8 from above the bed-plate the casing 6 is formed with a funnel-shaped opening 40 leading to an aperture 41 in the bearing bushing7. Directly above the funnel-shaped opening 40 the bedplate 1 is provided with a lubricant-aperture 42 which is normally sealed by the spring-pressed ball 43, i

From the foregoing description considered in connection with the accompanying drawing, the construction, manner of operation and several advantages of my improved loop-taker actuating means will be clearly and fully understood. It is apparent that such a device has a wide variety of uses, and it will be understood that the form, construction and arrangement of the several elements employed may be varied. Therefore, the privilege is reserved of 'resorting to all such legitimate changes therein as may be fairly embodied within the spirit and scope of the appended claims.

Having thus set forth the nature of the invention, what I claim herein is:-

1. In a rotary hook sewing machine, in cornmeans for imparting an accelerated rotation to bination, a loop-taker, and means for imparting to said loop-taker one accelerated and one retar 1ied revolution during each stitch-forming cyc e.

2. In a rotary hook sewing machine, in combination, an actuating shaft adapted to make one `complete rotation during each stitch-forming cycle, a loop-taker shaft, and variable speed mechanism connecting said shafts for imparting a plurality of rotations to the loop-taker shaft for each rotation of said actuating shaft, said variable speed mechanism producing a speed lacceleration in one rotation and a speed retardation in a succeeding rotation of said loop-taker shaft.

3. In a sewing machine, in combination, a

loop-taker relatively fast and slow complete successve rotations for each needle-reciprocation.

5. A sewing machine having in combination, a needle reciprocable in a fixed path, a loop-taker and means for imparting to said loop-taker a plurality of revolutions of diierent durations for each reciprocation. of the needle.

6. A sewing machine having, in combination, a needle reciprocable in a xed path, a loop-taker cooperating therewith, a loop-taker shaft, an actuating shaft making a single revolution for each needle-reciprocation, and means connecting said loop-taker shaft and saidactuating shaft for imparting to said loop-taker shaft a plurality of revolutions of dierent durations for each needlereciprocation.

7 A sewing machine having, in combination, a reciprocating needle, a loop-taker, a constant speed drive-shaft, and means connecting said drive-shaft to said loop-taker, said means including speed multiplying gearing and a variable motion driving connection between said drive shaft and said gearing.

8. In a sewing machine having a frame including a bed-plate, a reciprocatory needle, a loop-taker copperating with said needle in the formation of stitches, actuating mechanism for said loop-taker comprising a loop-taker actuating shaft, a loop-taker shaft, an intermediate shaft having its axis offset relative to the axis of said loop-taker actuating shaft, a crank-andlink connection between said actuating. and intermediate shafts, and speed multiplying gearing connecting said intermediate shaft with said loop-taker shaft.

9. In a sewing machine, a frame including a bed-plate, a reciprocatory needle, a loop-taker cooperating with said needle in the formation of stitches, a loop-taker actuating shaft, a troughshaped casing provided with spaced bearing journals for said actuating shaft, and means for detachably securing said casing to the under side of said bed-plate, whereby the looper mechanism for said loop-taker below said bed-plate, and a member detachably secured to the lower face of said bed-plate having the entire looptaker actuating mechanism below said bed-plate journaled therein.

1l. A sewing machine having a frame including a flat bed and a. hollow standard rising therefrom, a reciprocatory needle, a loop-taker, loop-taker actuating means below said bed, a trough-shaped member separate from said bed in which said loop-taker actuating means is mounted, said means including a shaft having an outboard extension below said hollow standard, and means extending downwardly through the hollow standard to drive said shaft, said trough-shaped member being detachably secured to and closed by the under side of said bed.

12. A sewing machine having a frame including a flat bed-plate and a standard rising therefrom, a reciprocatory needle, a loop-taker below said bed-plate and cooperating with said needle in the formation of stitches, a loop-taker actuating shaft, a loop-taker shaft, gears connecting said shafts in driving relation, and a casing detachably secured to the lower face of said. bed-plate having longitudinally spaced bearing journals for said actuating shaft and providing a housing and lubricant reservoir for said gears.

13. A sewing machine having a frame including a flat bed-plate and a standard rising therefrom, a reciprocatory needle, a loop-taker cooperating with said needle in the formation of plate and supporting and enclosing said looptaker actuating mechanism.

14. A sewing machine having a frame including abed-plate and'a standard rising therefrom, a reciprocatory needle, a loop-taker below said bed-plate and cooperating with said needle in the formation of stitches, a loop-taker actuating shaft, a loop-taker shaft, variable speed mechanism connecting said kshafts in driving relation, and a casing detachably secured to the lower face of said bed-plate having spaced bearing journals for said shafts and providing a housing and lubricant-reservoir for said variable speed mechanism.

15. A sewing machine having a frame including a flat bed-plate and a standard rising therefrom, a reciprocating needle, a loop-taker below said bed-plate and cooperating with said needle in the4 formation of stitches, a shaft supporting member disposed below the bed-plate, a looptaker shaft, an intermediate shaft, and a bobbincase opener shaft journaled in said member, and a single lubricant-conduit communicating with all of said shafts.

16. Ina sewing machine, a frame including a bed-plate and a hollow standard rising therefrom, a reciprocatory needle, a loop-taker cooperating With said needle in the formation of stitches, loop-taker actuating mechanism, said mechanism including a shaft having an outboard 105 extension below said hollow standard, a subframe having spaced bearings in which the entire loop-taker actuating mechanism below said bed plate is journaled and means for detachably securing said sub-frame to the under side of said 11() bed-plate, whereby the loop-taker actuating mechanism may be applied to the sewing machine as a unit.

MAX L. WATERMAN. 

